As this type of apparatus, there has been suggested an apparatus provided with: an engine; an automatic transmission having a main oil pump which rotates in synchronization with the output shaft of the engine; and an auxiliary oil pump for maintaining the operating oil pressure of the automatic transmission during the automatic stop of the engine (refer to a patent document 1). Here, in particular, there has been suggested a technique in which if the operating oil pressure of the automatic transmission drops to less than a predetermined value during the automatic stop of the engine, the engine is automatically restarted after the automatic transmission is changed into a neutral state, and the automatic transmission is changed into a state in which the driving force of the engine can be transmitted to drive wheels after the number of revolutions of the engine is increased to the predetermined number of revolutions.
Patent document 1: Japanese Patent Application Laid Open No. 2004-003425